1. Field of the Invention
The present invention pertains to a device for monitoring fetal and maternal vital signs. More particularly, the present invention pertains to a device particularly suited for detecting, displaying, and recording a representation of the maternal and fetal heartbeats, fetal movement, and fetal response to external stimuli, dramatically improving communication between a mother and her fetus.
My U.S. Pat. No. 4,672,975 is directed to a stethoscope device which provides a visual indication of the heartbeat of an entity by displaying a representation of the heartbeat using two differently sized light members, superimposed one on the other. In a preferred version, each of the light members is in the shape of a heart, and detected heartbeats are utilized to produce electrical signals which control illumination of the heart-shaped light members to simulate a pulsating or beating heart.
In some circumstances it is necessary to display representations of two heartbeats. By way of example, it may be desired to display representations of the heartbeats of a pregnant woman and her fetus. In addition to the diagnostic benefit from such a display, an education benefit will also result. For example, such a display can be helpful in explaining the pregnancy to an older sibling. Such an activity can provide the older sibling with a feeling of acquaintance with the baby brother and sister it is soon to have and thus a willingness to welcome the younger sibling into the family.
2. Description of the Prior Art
Various different types of pulse rate sensing devices are known in the prior art. For example, U.S. Pat. No. 4,301,808, which issued to H. Taus on Nov. 24, 1981, discloses an infrared type sensor adapted to be attached to a body part of an exercising individual. The sensor is connected to drive digital, analog or flashing displays, which allow the individual to monitor their heart rate during exercise. U.S. Pat. No. 4,679,570, which issued to W. Lund et al on July 14, 1987, discloses a phonocardioscope which utilizes an acoustical sensor for producing an analog electrical signal in response to the sounds of heartbeats. The monitored heartbeats may be stored in RAM for display on an LCD, or for subsequent print out. German Offenlegungsschrift No. 2646414, published Apr. 28, 1977, discloses a stethoscope having a diaphragm disposed adjacent a sound chamber. Sounds of an individual's heartbeat are transmitted from the diaphragm through the sound chamber to conventional acoustic ear phones, and also to a pair of microphones situated in the chamber. Electrical signals from the microphones flash a lamp in response to detected heartbeats. A photodiode receives light impulses from the lamp and increments a self-resetting frequency counter, which provides a pulse rate display.
U.S. Pat. No. 3,945,373, which issued to D. Tweed et al. on Mar. 23, 1976, discloses an electro-optical transducer for converting displacements of an individual's body into an analog electrical signal.
None of these devices provide two separate sensors for simultaneously monitoring the pulse rates of a mother and a fetus. Additionally, the prior art devices do not disclose the use of interactive circuitry to prevent erroneous monitoring of the same pulse rate by both sensors.